Various types of couplings are known in the art for the transmission of direction changing longitudinal movements to rotating bodies, in which the longitudinal movement, e.g. a Lifting movement, is transmitted by members that are in engagement. A simple example of this is a lever which engages in a circumferential groove of a rotating, longitudinally movable body and which is movable in the axial direction to cause the rotating body to undergo an axial movement.
To reduce friction between the moving parts, slide or ball bearings may be connected therebetween. However, couplings, in which a plurality of mechanical parts, such as, for example, levers, are in engagement with one another, have a certain amount of play and friction that cannot be neglected. If the longitudinal movement that is to be transferred to a rotating body is oriented centrally in the axial direction, errors of alignment between the lift generator and the rotating body may occur due to mechanical overdefinition. The term mechanical overdefinition means that the number of points for contact or supporting is higher than necessary so that the position between the lift generator and the rotating body may be not exactly defined.